1. Field of the Invention
The present invention relates to a biometric image pickup apparatus picking up, for example, an image of veins of a living organism.
2. Description of the Related Art
In recent years, the introduction of personal identification techniques (biometrics) using biometrics authentication into access control in a specific area or bank ATMs has begun. As such a method of identifying a living organism, methods using faces, fingerprints, voiceprints, irises, veins and the like as authentication data have been proposed. Among them, the shape pattern of veins under the skin of a finger or a palm hardly changes throughout a lifetime, and is information about the inside of a living organism, so it is difficult to forge, and the method using veins has high safety. Therefore, veins have been used frequently in biometrics authentication.
FIG. 5 shows a schematic view of a typical biometric image pickup apparatus. The biometric image pickup apparatus includes an upper cover 101 on which a light source 100 such as an LED (Light Emitting Diode) is mounted, a cover glass 102, an image pickup lens 103 and an image pickup device 104 such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). In the biometric image pickup apparatus 100, when a living organism 2 is placed on the cover glass 102, and light passes through the living organism 2 from the top thereof, light is absorbed by blood hemoglobin flowing through veins. Thereby, contrast is changed inside the living organism 2, and a change in contrast is received by the image pickup device 104, thereby vein data of the living organism 2 is capable of being obtained.
When the vein data is obtained in such a manner, light is absorbed by hemoglobin in a living organism to pick up an image, so as the light source (illumination light) 100, a light source emitting light of a wavelength which has transmittance through a living organism and is easily absorbed by hemoglobin is typically used (for example, refer to Japanese Patent No. 3797454).